WORD OF THE DAY

Organisms that can create their own light are bioluminescent. Though they're endangered, there are still many places in the world you can see bioluminescent fireflies blinking brightly in the dark.

A firefly or lightning bug's illumination is generated in its abdomen, where a chemical reaction produces photons that transmit light. The process varies among the many marine animals, fungi, and bacteria that are bioluminescent. A glowing squid native to the Pacific Ocean gets help from bioluminescent bacteria living inside its body, for example. Bio- means "relating to a living thing," and luminescent derives from the Latin lumen, "light."